REVISEDLHS - Revised Luyten Half-Second (LHS) Catalog

The Revised Luyten Half-Second (LHS) Catalog contains refined
coordinates and proper motion data for the high proper motion (HPM) stars
listed in the Original Luyten Half-Second (LHS) catalog. The positional
uncertainty in the Original LHS catalog is typically >10" and is often >30".
The authors of the Revised LHS Catalog used the digital scans of the Palomar
Observatory Sky Survey (POSS) I and POSS II plates to derive more accurate
positions and proper motions for these objects. Out of the 4470 candidates in
the LHS catalog, 4323 objects were manually re-identified in the POSS I and
POSS II scans. A small fraction of the stars were not found due to the lack
of finder charts and digitized POSS II scans. The uncertainties in the revised
positions are typically ~2", but can be as high as ~8" in a few cases,
which is a large improvement over the original data. Cross-correlation
with the Tycho-2 and Hipparcos catalogs yielded 819 candidates (with
red magnitude m_R <~12. For these brighter sources, the position and proper
motion data were replaced with the more accurate Tycho/Hipparcos data. In
total, there are revised proper motion measurements and coordinates for
4040 stars and revised coordinates for 4330 stars.

RA
The Right Ascension of the star for epoch 2000.0 and in the selected
equinox. This parameter was given in epoch and equinox J2000 and with a
precision of 0.01 seconds of time in the originating table. Bakos et al.
calculated the equatorial coordinates for epoch and equinox 2000.0 using their
astrometry and proper motion measurements. If none of the digital
scans of POSS plates were available, or the difference between the
epochs was not sufficient, proper motions from Luyten were accepted.
If the star was not found, both coordinates and proper motions were taken
from Luyten.

Dec
The Declination of the star for epoch 2000.0 and in the selected
equinox. This parameter was given in epoch and equinox J2000 and with a
precision of 0.1 arcseconds in the originating table. Bakos et al.
calculated the equatorial coordinates for epoch and equinox 2000.0 using their
astrometry and proper motion measurements. If none of the digital
scans of POSS plates were available, or the difference between the
epochs was not sufficient, proper motions from Luyten were accepted.
If the star was not found, both coordinates and proper motions were taken
from Luyten.

PM_Tot
The total proper motion of the star, in arcseconds per year. Bakos
et al. calculated the equatorial coordinates for epoch and equinox 2000.0
using their astrometry and proper motion measurements. If none of the digital
scans of POSS plates were available, or the difference between the epochs was
not sufficient, proper motions from Luyten were accepted. If the star was not
found, both coordinates and proper motions were taken from Luyten.

Position_Offset
The offset in arcseconds between the predicted J2000.0
positions of the star in the Original and Revised LHS Catalogs. A blank entry
indicates that no new position is available and that the listed coordinates
are taken from the Original LHS Catalog.

1 = DSS I image has poor quality.
2 = DSS II image has poor quality.
B = position shift between the two frames is less than 5", proper motion
data from LHS Catalogue is taken.
C = refitting of position was done (due to saturation or merging).
D = double star, or companion of a binary.
H = coordinates, proper motion and magnitudes are from the Tycho-2
Supplement-1 catalogue, i.e. from the Hipparcos catalogue (<I/239>).
I = identification dubious.
L = for some reason the new proper motion measurement is not accurate,
Luyten's data are used. (The HEASARC changed the value of this flag
from 'b' to 'L' to avoid confusion).
M = merging.
N = star was not found in manual search.
P = POSS II DSS frame was not available.
S = saturated on at least one of the frames.
T = coordinates, proper motion and magnitudes are from the
Tycho-2 catalogue (<I/259>).
W = finder chart would have been needed for manual identification, but it
was not available.

Luyten_RA_J2000
The Right Ascension (J2000 equator and epoch) of the star
as listed in the Original (1979 version) LHS Catalog.

Luyten_Dec_J2000
The Declination (J2000 equator and epoch) of the star
as listed in the Original (1979 version) LHS Catalog.

Luyten_PM_Tot
The total proper motion of the star, in arcseconds per year,
as listed in the Original (1979 version) LHS Catalog.

Luyten_PM_Dir
The position angle of the proper motion of the star, in
degrees, as listed in the Original (1979 version) LHS Catalog.

POSS_I_Epoch
The epoch of the POSS I plate in which the position of the
measured.

POSS_II_Epoch
The epoch of the POSS II plate in which the position of the
measured.

Red_Mag
The "Red" magnitude of the star. The red magnitude is taken from
the Tycho Catalog V magnitude if the star was found in the Tycho-2
(Supplement-1) Catalog (CDS Cat. <I/259>, otherwise it is the Original LHS
(CDS Cat. <I/87>) red magnitude.

Blue_Mag
The "Blue" Magnitude of the star. The blue magnitude is taken from
the Tycho Catalog B magnitude if the star was found in the Tycho-2
(Supplement-1) Catalog (CDS Cat. <I/259>, otherwise it is the Original LHS
(CDS Cat. <I/87>) photographic magnitude.